Calcopirita

M. SOKI], I. ILI], D. @IVKOVI], N. VU^KOVI]

ISSN 0543-5846 METABK 47(2) 109-113 (2008) UDC - UDK 549.324.31:66.094.3=111

INVESTIGATION OF MECHANISM AND KINETICS OF CHALCOPYRITE CONCENTRATE OXIDATION PROCESS
Received – Prispjelo: 2007-03-06 Accepted – Prihva}eno: 2007-11-31 Original Scientific Paper – Izvorni znanstveni rad

The oxidation process of chalcopyrite concentrate ″Rudnik″(Serbia) was investigated by DTA-TG measurements under air conditions in the temperature range of 298 – 1173 K, as well as by XRD analysis of the oxidation products at 723, 873 and 1173 K. Based on the results obtained, the mechanism of chalcopyrite concentrate oxidation process was given, contributing to the understanding of the successive chemical reactions accompanying the formation of intermediateproducts. The kinetic study of the investigated process was done according to the methods of Kissinger and Ozawa, which enabled determination of the activation energy values of the chemical reactions proceeding during the chacopyrite concentrate oxidation. Key words: chalcopyrite, oxidation, DTA-TG, XRD, kinetics Istra`ivanje mehanizma i kinetika procesa oksidacije halkopiritnog koncentrata.Proces oksidacije halkopiritnog koncentrata ″Rudnik″ (Srbija) ispitivan je DTA-TG mjerenjima u atmosferi zraka i temperaturnom intervalu 298–1173 K, kao i XRD analizama produkata oksidacije na 723, 873 i 1173 K. Na temelju dobijenih rezultata predlo`en je mehanizam oksidacije halkopiritnog koncentrata uklju~uju}i i kemijske reakcije koje prate stvaranje odgovaraju}ih me|uproizvoda. Za ispitivanjekinetike procesa rabljene su metode Kissinger i Ozawa, kojima su odre|ene vrijednosti energija aktivacije kemijskih reakcija tokom oksidacije halkopiritnog koncentrata. Klju~ne rije~i: halkopirit, oksidacija, DTA-TG, XRD, kinetika

INTRODUCTION
The roasting of chalcopyrite, the most exploited copper mineral, presents a very important step in the copper extraction during the traditionalsmelting-refining process, as well as in advanced processes in copper metalurgy [1-2]. Consequently, numerous researches have been investigated, in order to study the chalcopyrite oxidative roasting parameters, its mechanism and reactions involved [1-16]. These references deal with pure chalcopyrite mineral oxidation and with the oxidation process of chalcopyrite concentrates, also. Although there are slightdifferences in the sequence of phase changes occurring in Cu-Fe-S-O system [1, 5, 6, 10], following main reactions proceed during the roasting of chalcopyrite as suggested in [1]: (1) 2CuFeS2 + 7.5O2 ® 2CuSO4 + Fe2O3 + 2SO2 (2) 2CuFeS2 ® Cu2S + 2FeS + S Meunier at al. [3] studied the behaviour of pieces of chalcopyrite in a stream of air at 573-1173 K. At the temperature of 773 K a layer of bornitesurrounded by Fe2O3 and CuSO4 was found. At 1073 K, CuO and
M. Soki}, N. Vu~kovi}, ITNMS, Belgrade, Serbia, I. Ili}, Faculty of Technology and Metallurgy, University of Belgrade, Serbia, D. @ivkovi}, Technical Faculty at Bor, University of Belgrade, Serbia

Fe2O3 with CuFe2O4 were formed. From sulphide ores, the formation of copper sulphate was also reported [4]. Heating in presence of air at773-823 K transforms the sulphides to sulphates and oxides at higher temperature, which was confirmed by microscopic studies. The complexity of the chalcopyrite oxidation process makes this topic still an interesting one, due to the number of reactions being occured simultaneously and frequently influencing one another. As a contribution to the better knowledge of this process, the mechanism andkinetics of the oxidation process of chalcopyrite concentrate from ''Rudnik'' mine (Serbia), using comparative analysis of data obtained by DTA-TG measurements and XRD of oxidation products at selected temperatures, are presented in this paper.

EXPERIMENTAL
The chalcopyrite concentrate from ''Rudnik'' mine (Serbia), having chemical composition presented in Table 1, was used for experimental...