Academic Journal of Science, CD-ROM. ISSN: 2165-6282 :: 2(1):61 65 (2013) Copyright c 2013 by UniversityPublications.net LEACHING OF CHALCOPYRITE CONCENTRATE (CuFeS 2 ) IN NITRIC ACID (HNO 3 ) SOLUTION Tevfik A açayak and Ali Aras Selcuk University, Turkey The leaching conditions of chalcopyrite (CuFeS 2 ) concentrate taken from Koyulhisar (Sivas, Turkey) in a nitric acid medium were investigated by studying the effects of its leaching parameters, such as stirring speed, temperature and nitric acid concentration on Cu extraction. It was found that stirring speed has a little effect on the leaching. Copper extraction from chalcopyrite is directly proportional to nitric acid concentration. As the temperature increases, copper extraction also increases. The maximum copper extraction was obtained in 180 min of leaching time with the following conditions; 400 rpm stirring speed, 4.0 M nitric acid concentration and 80 C leaching temperature. Keywords: Chalcopyrite concentrate, Leaching, copper extraction, Nitric acid. Introduction Copper generally occurs as sulphide, oxide, carbonate, silicate minerals and native in the nature. The minerals used in copper production are 50% of chalcocite (Cu 2 S), 25% of chalcopyrite (CuFeS 2 ), 3% of enargite (CuAsS 4 ), 6% of native copper, 15% of oxide and 1% of other sulphide minerals (covellite, bornite, tetrahedrite) (Akdag, 1992). Chalcopyrite is the most important copper sulphide mineral. It is generally associated with other sulphide minerals, such as sphalerite (ZnS), pyrite (FeS 2 ) and galena (PbS). These minerals are generally separated from each other by flotation. Production of copper is performed with pyrometallurgical and hydrometallurgical processes. 20% of world copper production is obtained by hydrometallurgical processes, the rest is pyrometallurgically. While pyrometallurgical processes is applied to sulphide minerals, hydrometallurgical processes is applied to oxide copper ores. Because of environment problems caused from pyrometallurgical processes, interest shown to hydrometallurgical processes increased and researches were performed to replace the pyrometallurgical processes recently (Canbazoglu, 2001). Hydrometallurgical processes can be typically categorized as chloride, sulfate, nitrate and ammonia leaching and bioleaching. Many studies on the dissolution of chalcopyrite using different solutions have been performed by many researchers (Prasad and Pandey, 1998; Majima et al., 1985; Dutrizac,1981,1989,1990; Arslan et al., 2004; Havlik et al.,1995, 2005; Mikhlin et al., 2004; Lu et al., 2000; Saxena and Mandre, 1992; Tchoumou and Roynette, 2007; McDonald and Muir, 2007; Akcil and Ciftci, 2003; Dreisinger, 2006; Hackl et al., 1995; Aydogan et al., 2006; Misra and Fuerstenau, 2005; Mahajan et al., 2007; Antonijevi et al., 1994, 2004; Padilla et al., 2007; Al-Harahsheh et al., 2005). In this study, the leaching conditions of chalcopyrite (CuFeS 2 ) concentrate taken from Koyulhisar (Sivas, Turkey) in a nitric acid medium were investigated by studying the effects of its leaching parameters, such as stirring speed, temperature and nitric acid concentration on Cu extraction. 61
62 Tevfik Aǧacayak and Ali Aras Material and Method Samples of the chalcopyrite concentrate were taken from the Menka Flotation Plant (Sivas, Turkey), where the CuFeS 2 PbS ZnS complex ore is enriched. The particle size of the concentrate was -212 m. The concentrate was wet sieved to obtain different particle size fractions. The chemical analysis of each size fraction is given in Table 1. Table 1. The chemical analysis of each size fraction. Particle size Cu (%) Pb (%) Zn (%) Fe (%) (µm) -212+150 27.26 0.69 0 28.65-150+106 25.78 0.70 0.52 27.90-106+75 25.19 1.22 1.72 28.69-75+53 24.85 1.53 3.10 27.71-53+38 24.30 3.01 4.62 28.38-38 25.61 10.80 3.40 25.84 A 1-liter glass beaker was used as a leaching reactor placed in a temperature-controlled water bath. Heidolph RZR 2021 model brand mechanic mixer for the mixing process was used. 2 ml of leaching solution, were taken at different times. Copper in the leaching solution was determined using GBC SensAA model flame atomic absorption spectrometer (AAS). Result and Discussion Effect of Stirring Speed The effect of stirring speed on the dissolution of chalcopyrite concentrate was investigated in a solution of 4 M HNO 3 at 60 C in the range of 100 to 400 rpm. Experiments at different stirring rates are illustrated in Figure 1. The results of these experiments show that an increase in stirring speed increases the Cu extraction. 400 rpm was selected as the optimum operating stirring speed. Figure 1. The effect of stirring speed on copper extraction.
Leaching of Chalcopyrite Concentrate... 63 Effect of Nitric Acid Concentration The effect of acid concentration on the dissolution of chalcopyrite concentrate was investigated by using 3 different HNO 3 concentrations (1.0, 2.0 and 4.0 mol L 1 ). In these experiments, the reaction temperature was kept constant as 60 C, particle size as -75+53 µm, solid/liquid ratio as 0.002 g ml 1 and stirring speed as 400 rpm. The results, as showed in Figure 2, show that the Cu extraction increases as acid concentration increases. Figure 2. The effect of HNO 3 concentration on copper extraction. Effect of Temperature The effect of temperature was investigated for the leaching temperatures of 50, 60, 70, 80 C. During the test, HNO 3 concentration of the solution (4 M), stirring speed (400 rpm), leaching time (3 hours) and pulp density (1/500 solid to liquid ratio) were kept constant. The results of the experiments are presented in Figure 3. Figure shows that an increase in temperature increases the Cu extraction. Figure 3. The effect of temperature on copper extraction.
64 Tevfik Aǧacayak and Ali Aras Conclusion In this study, the extraction of Cu from chalcopyrite concentrate in nitric acid solution was studied. It was determined that the copper extraction increased with increasing stirring speed, nitric acid concentrations, temperature and leaching time. Optimum leaching conditions were determined as 80 C leaching temperature, 1/500 g/ml for solidto-liquid ratio, 4.0 M for HNO 3 concentration, 400 rpm for stirring speed and 180 minutes for leaching time. Under these optimum process conditions, the extraction of copper from chalcopyrite concentrate in nitric acid solution was about 80 %. Acknowledgements This study was supported by The Research Foundation of Selcuk University under Project No. BAP- 12701742. References 1. Akdag, M., 1992, Üretim Metalurjisi, S. 259 262, Dokuz Eylül Ün. Müh. Fak.. Yay nlar, zmir. 2. Akcil, A., Ciftci, H., 2003. Metals recovery from multimetal sulphide concentrates (CuFeS 2 PbS ZnS): combination of thermal process and pressure leaching. International Journal of Mineral Processing 71 (1 4), 233 246. 3. Al-Harahsheh, M., Kingman, S., Hankins, N., Somerfield, C., Bradshaw, S., Louw,W., 2005. The influence of microwaves on the leaching kinetics of chalcopirite. Minerals Engineering 18, 1259 1268. 4. Antonijevi, M.M., Jankovi, Z.D., Dimitrijevi, M.D.,1994. Investigation of the kinetics of chalcopyrite oxidation by potassium dichtomate. Hydrometallurgy 35, 187 201. 5. Antonijevi, M.M., Dimitrijevi, M.D., Jankovi, Z.D., 1997. Leaching of pyrite with hydrogen peroxide in sulphuric acid. Hydrometallurgy 46, 71 83. 6. Antonijevi, M.M., Jankovi, Z.D., Dimitrijevi, M.D., 2004. Kinetics of chalcopyrite dissolution by hydrogen peroxide in sulphuric acid. Hydrometallurgy 71, 329 334. 7. Arslan, F., Bulut, G., Kangal, M.O., Perek, K.T., Gul, A., Gurmen, S., 2004. Studies on leaching of massive rich copper ore in acidic ferric sulfate solutions. Scandinavian Journal of Metallurgy 33, 6 14. 8. Aydogan, S., Ucar, G., Canbazoglu, M., 2006. Dissolution kinetics of chalcopyrite in acidic potassium dichromate solution. Hydrometallurgy 81, 45 51. 9. Canbazoglu, M., 2001, Çözelti Madencili i Ders Notlar, s.18-24, Cumhuriyet Ün. Müh. Fak. Maden Müh. Böl., Sivas. 10. Dreisinger, D., 2006. Copper leaching from primary sulfides: options for biological and chemical extraction of copper. Hydrometallurgy 83, 10 20. 11. Dutrizac, J.E., 1981. The dissolution of chalcopyrite in ferric sulphate and ferric chloride media. Metallurgical Transactions B, Process Metallurgy 12B, 371 378. 12. Dutrizac, J.E., 1982. Ferric ion leaching of chalcopyrites from different localities. Met. Trans. B 13B, 303 309. 13. Dutrizac, J.E., 1989. Elemental sulphur formation during the ferric sulphate leaching of chalcopyrite. Can. Metall. Q. 28, 337 344. 14. Dutrizac, E., 1990. Elemental sulphur formation during the ferric chloride leaching of chalcopyrite. Hydrometallurgy 23, 153 176. 15. Hackl, R.P., Dreisinger, D.B., Peters, E., King, J.A., 1995. Passivation of chalcopyrite during oxidative leaching in sulfate madia. Hydrometallurgy 39, 25 48. 16. Havlik, T., Škrobian, M., Balaž, P., Kammel, R., 1995. Leaching of chalcopyrite concentrate with ferric chloride. Int. J. Miner. Process. 43, 61 72.
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