The increasing complexity of ore resources and recycled materials in the feed of pyrometallurgical
processes present a technical challenge to the metallurgical engineers working on maximising the
recovery of the valuable elements and minimising the environmental impact of the processes. To
address this challenge, the availability of computational tools that can predict the mass and energy
balance in complex systems is required. Then the accurate description of phase equilibria in the
complex multicomponent systems describing the chemistry of the pyrometallurgical processes
becomes critical for the correct implementation of the indicated tools and facing the outlined industrial
challenges.
In the present study the distribution of selected elements (Pb, Zn, Fe, As, Sn, Sb, Bi and Ni) between
oxide liquid and metal in the ‘CuO0.5’-CaO-AlO1.5 system in equilibrium with Cu metal at 1400°C
(liquidus of CaAl2O4) was experimentally studied using the equilibration and quenching technique
followed by the electron probe X-ray microanalysis of the resulted samples. The study covered a
wide range of effective p(O2) over the system from 10-11 to 10-3.5 (corresponding to formation of
immiscible CuO0.5-rich slag). To avoid loss of volatile elements (Pb, Zn, As, Sn, Sb and Bi), a
correlation between ‘CuO0.5’ in oxide liquid and p(O2) in open system was obtained first, followed by
studying the volatile elements distribution in closed conditions (Al2O3 crucible sealed in SiO2
ampoule), where ‘CuO0.5’ concentration was used as a marker to evaluate the effective p(O2) over
the system.
The experimental results were then used for the optimisation of the thermodynamic model
parameters of the system as part of the integrated experimental and self-consisting thermodynamic
modelling research program of phase equilibria in the Cu-Pb-Zn-Fe-Ca-Si-Al-Mg-O-S-(As, Sn, Sb,
Bi, Ag, Au, Ni, Cr, Co and Na) gas/oxide liquid/matte/speiss/metal/solids system.