@conference{
author = "Sokić, Miroslav and Marković, Branislav and Štrbac, Nada and Kamberović, Željko and Manojlović, Vaso and Matković, Vladislav and Bugarčić, Mladen",
year = "2017",
abstract = "The determination of mechanism of the polymetallic concentrate leaching with sulfuric
acid and hydrogen peroxide was done based on the characterization of the starting
concentrate and leach residues. The application of XRD and thermal analysis on the
leaching mechanism determination was done. The phase content of concentrate and leach
residues were determined by X-ray analysis using diffractometer PHILIPS PW-1710. DTA
and TG analysis were performed in air atmosphere up to 1173 K on NETZSH, model 409
EP, device.
The polymetallic concentrate, used in experiments, has the following chemical
composition (in wt. %): Cu-8.92, Zn-8.79; Pb-12.66, Fe-19.80 and S-21.4. X-ray phase
analysis of the concentrate reveals that the sample contains chalcopyrite, sphalerite, galena
pyrhotite and quartz (Fig. a). On Fig. b the DTA and TG curves of polymetallic concentrate
are shown. Curves include two parts: first, a low temperature, which correspond to the
sulfides oxidation (the mass increase on the TG, and exothermic peaks on the DTA); and
second which correspond to the dissociation of sulphates and oxysulphates (the mass loss
on the TG, and endothermic peaks on the DTA).
The phases identified in the leach residue by XRD were elemental sulphur, anglesite,
chalcopyrite, sphalerite, galena pyrhotite and quartz (Fig. c), which confirms that the
elemental sulphur is formed during leaching. In Fig. d the TG-DTA curve of the leach
residue are shown. On DTA curve on the temperature of 118 oC, the endothermic peak as a
result of elemental sulfur melting is clearly visible. Then, in the range of 250-350 oC,
weight loss as a consequence of the oxidation of sulfur to SO2 gas occurs. The loss of mass
due to combustion of sulfur on Fig. d is smaller than the sulfide sulfur which is oxidized
during the leaching process, which indicates that the sulfur from sulfides is oxidised both
to the sulfate and to the elemental form. The mass increase followed by exothermic effects
in the range of 400-700 oC is a result of the oxidation of unleached sulphides in the solid
residues. At temperatures above 720 °C weight loss occurs as a result of dissociation of
sulphate and oxysulphates of lead, zinc, copper and iron with endothermic peaks on the
DTA curve. XRD and DTA/TG studies have contributed in determining the mechanism of
polymetallic concentrate leaching process in the system H2SO4-H2O2-H2O:CuFeS2 + 5/2H2O2 + 5/2H2SO4 = CuSO4 + 1/2Fe2(SO4)3 + 2S0 + 5H2O
(1)
CuFeS2 + 17/2H2O2 + 1/2H2SO4 = CuSO4 + 1/2Fe2(SO4)3 + 9H2O(2)
ZnS + H2O2 + H2SO4 = ZnSO4 + S0 + 2H2O (3)
ZnS + 4H2O2 = ZnSO4 + 4H2O (4)
PbS + H2O2 + H2SO4 = PbSO4 + S0 + 2H2O (5)
PbS + 4H2O2 = PbSO4 + 4H2O (6)",
publisher = "Kosovska Mitrovica : Fakultet Tehničkih nauka",
journal = "Osmi simpozijum o termodinamici i faznim dijagramima",
title = "Mechanism of polymetallic concentrate leaching with sulfuric acid and hydrogen peroxide solution",
pages = "88-86"
}
