Document Type: Original Research Paper


Department of mining Engineering, Tarbiat Modares University, Tehran, Iran



Copper oxide minerals such as malachite do not respond well to the traditional copper sulfide collectors, and require alternative flotation schemes. In many copper ore mines, significant copper oxide minerals, especially malachite, are associated with sulfide minerals. Considering that xanthates are most widely used in the flotation of sulfide minerals as well as copper sulfide minerals and, hydroxamate has shown a good selectivity for copper oxide minerals. Use of the synergistic effect of xanthate and hydroxamate can be an effective way to increase the flotation efficiency of copper oxide minerals along with sulfide minerals. In this work, we investigate the individual interactions of potassium amyl xanthate (PAX) and potassium alkyl hydroxamate (HXM) with the natural malachite and explore their synergistic effects on the malachite flotation. The results of solubility of malachite in collector solutions, changes in the malachite surface potential, adsorption kinetics, adsorption densities, dynamic contact angles, FT-IR analyses, and small-scale flotations, are discussed. The results obtained demonstrate that PAX and HXM are chemically co-adsorbed on the malachite surface, and the amount of PAX adsorbed on the malachite surface is considerably increased in the mixed PAX/HXM systems because of the co-adsorption mechanism. The flotation results confirm that the mixed PAX/HXM exhibit a superior flotation performance of malachite compared to the individual system of PAX or HXM. Based on these results, the mixed PAX/HXM exhibit a remarkable synergism effect on malachite surface hydrophobicity.


[1]. Marion, C., Jordens, A., Li, R., Rudolph, M. and Waters, K.E. (2017). An evaluation of hydroxamate collectors for malachite flotation. Separation and Purification Technology, 183, 258-269.

[2]. Lee, J.S., Nagaraj, D.R. and Coe, J.E. (1998). Practical aspects of oxide copper recovery with alkyl hydroxamates. Minerals Engineering. 11 (10): 929-939.

[3]. Li, Z. (2019). Effect of salinity and overgrinding on the flotation of malachite

[4]. Fuerstenau, M.C. and Han, K.N. (2002). Metal–surfactant precipitation and adsorption in froth flotation. Journal of colloid and interface science. 256 (1): 175-182.

[5]. Lee, K., Archibald, D., McLean, J. and Reuter, M.A. (2009). Flotation of mixed copper oxide and sulphide minerals with xanthate and hydroxamate collectors. Minerals engineering. 22 (4): 395-401.

[6]. Lenormand, J., Salman, T. and Yoon, R.H. (1979). Hydroxamate flotation of malachite. Canadian Metallurgical Quarterly. 18 (2): 125-129.

[7]. Fuerstenau, D.W., Herrera-Urbina, R. and McGlashan, D.W. (2000). Studies on the applicability of chelating agents as universal collectors for copper minerals. International Journal of Mineral Processing, 58(1-4), 15-33.

[8]. Srdjan, M.B. (2010). Handbook of Flotation Reagents: Chemistry, Theory and Practice: Volume 2: Flotation of Gold, FGM and Oxide Minerals.

[9]. Jiayang, H., Jianlong, D., Wentao, L., Bin, Y. and Beijun, L. (2013). Molecular modeling of alkyl hydroxamates as a highly selective flotation collectors for oxidized copper mineral. 2nd International Symposium on Instrumentation and Measurement, Sensor Network and Automation (IMSNA) (pp. 353-356). IEEE.

[10]. Rybinski, V,W. Schwuger, M.J. and Dobias, B. (1987). Surfactant mixtures as collectors in flotation. Colloids and surfaces, 26, 291-304.

[11]. Chowdhury, R. and Antolasic, F. (2012). Structural analysis of hydroxamate reagents by X-ray diffraction. Journal of Earth Science and Engineering. 2 (10): 584.

[12]. Hope, G.A., Woods, R., Parker, G.K., Buckley, A.N. and McLean, J. (2010). A vibrational spectroscopy and XPS investigation of the interaction of hydroxamate reagents on copper oxide minerals. Minerals Engineering. 23 (11-13): 952-959.

[13]. Li, Z. (2019). Effect of salinity and overgrinding on the flotation of malachite.

[14]. Buckley, A.N., Denman, J.A. and Hope, G.A. (2012). The adsorption of n-octanohydroxamate collector on Cu and Fe oxide minerals investigated by static secondary ion mass spectrometry. Minerals. 2 (4): 493-515.

[15]. Hope, G.A., Buckley, A.N., Parker, G.K., Numprasanthai, A., Woods, R. and McLean, J. (2012). The interaction of n-octanohydroxamate with chrysocolla and oxide copper surfaces. Minerals Engineering, 36, 2-11.

[16]. Mendiratta, N.K. (2000). Kinetic studies of sulfide mineral oxidation and xanthate adsorption (Doctoral dissertation, Virginia Tech).

[17]. Zhang, Y., Cao, Z., Cao, Y. and Sun, C. (2013). FTIR studies of xanthate adsorption on chalcopyrite, pentlandite and pyrite surfaces. Journal of Molecular Structure, 1048, 434-440.

[18]. Mielczarski, J. and Leppinen, J. (1987). Infrared reflection-absorption spectroscopic study of adsorption of xanthates on copper. Surface Science. 187 (2-3): 526-538.

[19]. Mielczarski, J. and Leppinen, J. (1987). Infrared reflection-absorption spectroscopic study of adsorption of xanthates on copper. Surface Science. 187 (2-3): 526-538.

[20]. Rao, S.R. and Finch, J.A. (2003). Base metal oxide flotation using long chain xanthates. International Journal of Mineral Processing. 69 (1-4): 251-258.

[21]. Davidson, M.S. (2009). An investigation of copper recovery from a sulphide oxide ore with a mixed collector system. In Masters Abstracts International (Vol. 49, No. 02).

[22]. Heyes, G.W., Allan, G.C., Bruckard, W.J. and Sparrow, G.J. (2012). Review of flotation of feldspar. Mineral Processing and Extractive Metallurgy. 121 (2): 72-78.

[23]. Cui, X., Jiang, Y., Yang, C., Lu, X., Chen, H., Mao, S. and Du, Y. (2010). Mechanism of the mixed surfactant micelle formation. The Journal of Physical Chemistry B. 114 (23): 7808-7816.

[24]. Buckley, A.N., Hope, G.A., Parker, G.K., Steyn, J. and Woods, R. (2017). Mechanism of mixed dithiophosphate and mercaptobenzothiazole collectors for Cu sulfide ore minerals. Minerals Engineering. 109: 80-97.

[25]. Xu, L., Tian, J., Wu, H., Lu, Z., Sun, W. and Hu, Y. (2017). The flotation and adsorption of mixed collectors on oxide and silicate minerals. Advances in colloid and interface science. 250: 1-14.

[26]. Lotter, N.O. and Bradshaw, D.J. (2010). The formulation and use of mixed collectors in sulphide flotation. Minerals engineering, 23(11-13), 945-951.

[27]. Xu, L., Hu, Y., Tian, J., Wu, H., Wang, L., Yang, Y. and Wang, Z. (2016). Synergistic effect of mixed cationic/anionic collectors on flotation and adsorption of muscovite. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 492, 181-189.

[28]. Li, F., Zhong, H., Xu, H., Jia, H. and Liu, G. (2015). Flotation behavior and adsorption mechanism of α-hydroxyoctyl phosphinic acid to malachite. Minerals engineering. 71: 188-193.

[29]. Liu, G., Huang, Y., Qu, X., Xiao, J., Yang, X. and Xu, Z. (2016). Understanding the hydrophobic mechanism of 3-hexyl-4-amino-1, 2, 4-triazole-5-thione to malachite by ToF-SIMS, XPS, FT-IR, contact angle, zeta potential and micro-flotation. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 503, 34-42.

[30]. Yin, W.Z., Sun, Q.Y., Dong, L.I., Yuan, T.A.N.G., Fu, Y.F. and Jin, Y.A.O. (2019). Mechanism and application on sulphidizing flotation of copper oxide with combined collectors. Transactions of Nonferrous Metals Society of China. 29 (1): 178-185.

[31]. Liu, J., Hu, Z., Liu, G., Huang, Y. and Zhang, Z. (2020). Selective flotation of copper oxide minerals with a novel Amino-Triazole-Thione surfactant: a comparison to hydroxamic acid collector. Mineral Processing and Extractive Metallurgy Review. 41 (2): 96-106.

[32]. Fuerstenau, D.W. (1983). The adsorption of hydroxamate on semi-soluble minerals. Part I: Adsorption on barite, Calcite and Bastnaesite. Colloids and Surfaces. 8 (2): 103-119.

[33]. Mohseni, M., Abdollahy, M., Poursalehi, R. and Khalesi, M.R. (2018). An insight into effect of surface functional groups on reactivity of Sphalerite (110) surface with Xanthate collector: a DFT study. Journal of Mining and Environment. 9 (2): 431-439.

[34]. Stoilova, D., Koleva, V. and Vassileva, V. (2002). Infrared study of some synthetic phases of malachite (Cu2 (OH) 2CO3)–hydrozincite (Zn5 (OH) 6 (CO3) 2) series. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 58 (9): 2051-2059.

[35]. Li, Z., Rao, F., Song, S., Uribe-Salas, A. and López-Valdivieso, A. (2020). Reexamining the adsorption of octyl hydroxamate on malachite surface: Forms of molecules and anions. Mineral Processing and Extractive Metallurgy Review. 41 (3): 178-186.