Redistribution of Minor and Trace Elements During Roasting of Cu-Rich Complex Concentrate in Inert Atmosphere

Abstract

Abstract A Cu-rich polymetallic complex concentrate produced at the Garpenberg Mines of Boliden Mineral AB, Sweden is investigated. Roasting at 700 °C in N2 leads to extensive liquid formation. The calcine obtained after cooling down to the room temperature is found to be severely sintered, entrapping numerous melt nuggets. This work focuses on analyzing redistribution of the minor (Ag) and trace elements consequent to the roasting treatment. Advanced micro-analytical techniques such as quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), laser-ablation inductively coupled plasma-mass spectrometry (ICP-MS) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) are used in conjunction for detailed characterization of the initial concentrate and the roasted calcine, especially the melt nuggets (which symbolizes the phases which were molten at 700 °C). The minor element—Ag is primarily in the silver-antimonide and tetrahedrite mineral phases in the initial concentrate. Ag separates out of tetrahedrite when the later interacts with galena to form a liquid phase. Furthermore, Mn, Cd, Tl and Hg are the relevant trace elements in the Garpenberg concentrate. Sphalerite is the major host of Mn, Cd and Hg. Tl is mainly in galena. Consequent to liquid formations at 700 °C, the trace elements redistribute and tend to segregate in low-melting phase-fractions. Statistical methods such as correlation matrices and clustering analysis are used effectively in evaluating the data from laser-ablation ICP-MS measurements on sulphide samples. Graphical Abstract