Mineral chemistry and phase equilibrium constraints on the origin of accretions formed during copper flash smelting
This paper delves into the constraints on the nature, origin and thermal evolution of the accretions formed in the uptake shaft of the flash smelting furnace operated by Atlantic Copper in Huelva, Spain, outlining recommended practices for preventing accretion buildup. The accretions were investigated using quantitative electron probe microanalysis, X-ray diffraction and digital imaging techniques, and the experimental data on mineral composition, crystal chemistry and textural relationships were interpreted in terms of thermodynamic phase equilibrium in the SiO2-Fe-O-S system. The results suggest that two distinct types of accretions were formed by the fractional crystallization of two coexisting immiscible melts, under changing conditions of oxygen partial pressure (pO2). The type I accretion of magnetite + delafossite ± cuprite ± tridymite ± metallic copper crystallized from a fractionating copper-rich melt at pO2 above about 10−5 atm, while the type II accretion of magnetite + fayalite + metallic copper + chalcocite derived from a melt with lower copper concentration when pO2 levels dropped below that critical level. Phase compositions and textures were consistent with a cooling history of both compositionally contrasting liquids from about 1,250 °C, the liquidus temperature of magnetite, to eutectic or near-eutectic temperatures of around 1,100 °C. The maintenance of appropriate temperatures — above the liquidus temperature of magnetite — and oxygen partial pressure levels may be critical for the prevention of accretion buildup.
Key wordsCopper metallurgy Flash furnace Accretion Matte Slag Cu-Fe-O-Si system
Unable to display preview. Download preview PDF.
- Fernández-Caliani, J.C., Ríos, G., Martínez, J., and Jiménez, F., 2012, “Occurrence and speciation of copper in slags obtained during the pyrometallurgical processing of chalcopyrite concentrates at the Huelva smelter (Spain),” Journal of Mining and Metallurgy B, Vol. 48, pp. 161–171, https://doi.org/10.2298/jmmb111111027f.CrossRefGoogle Scholar
- Miettinen, E., 2008, “Thermal Conductivity and Characteristics of Copper Flash Smelting Flue Dust Accretions,” Ph.D. Thesis, Helsinki University of Technology, 87 pp.Google Scholar
- Osborn, E.F., and Muan, A., 1960, “Phase Equilibria Diagrams of Oxide Systems. The System FeO-Fe2O3-SiO2,” American Ceramic Society & Edward Orton Jr. Ceramic Foundation, Columbus, Ohio, USA.Google Scholar
- Ríos, G., Ramírez, R., Ruíz, I., and González, I. 2013, “Recovery of nickel from bleeding electrolyte plant at Atlantic Copper,” Proceedings of the 8th International Copper/Cobre Conference, Santiago de Chile, Chile.Google Scholar
- Stefanova, V., Shentov, D., Mihailova, I., and Iliev, P., 2012, “Investigation of the phase composition of accretions formed into WHB under flash smelting of copper concentrates,” Russian Journal of Non-Ferrous Metals, Vol. 53, pp. 26–32, https://doi.org/10.3103/s106782121201021x.CrossRefGoogle Scholar
- Swinbourne, D.R., Simak, E., and Yazawa, A., 2002, “Accretion and dust formation in copper smelting. Thermodynamic considerations”, Proceedings of the International Symposium on Sulfide Smelting, Seattle, WA, pp. 247–259.Google Scholar