Investigation of Liquidus Temperatures and Phase Equilibria of Copper Smelting Slags in the FeO-Fe2O3-SiO2-CaO-MgO-Al2O3 System at PO2 10−8 atm

Abstract

Copper concentrates and fluxes can contain variable levels of SiO 2 , CaO, and MgO in addition to main components Cu, Fe, and S. Metal recovery, slag tapping, and furnace wall integrity all are dependent on phase equilibria and other properties of the phases and are functions of slag composition and operational temperature. Optimal control of the slag chemistry in the copper smelting, therefore, is essential for high recovery and productivity; this, in turn, requires detailed knowledge of the slag phase equilibria. The present work provides new phase equilibrium experimental data in the FeO-Fe 2 O 3 -SiO 2 -CaO-MgO-Al 2 O 3 system at oxygen partial pressure of 10 À8 atm within the range of temperatures and compositions directly relevant to copper smelting. For the range of conditions relevant to the Kennecott Utah Copper (South Magna, UT) smelting furnace, it was confirmed experimentally that increasing concentrations of MgO or CaO resulted in significant decreases of the tridymite liquidus temperature and in changes in the position of the tridymite liquidus in the direction of higher silica concentration; in contrast, the spinel liquidus temperatures increase significantly with the increase of MgO or CaO. Olivine and clinopyroxene precipitates appeared at high MgO concentrations in the liquid slag. The liquidus temperature in the spinel primary phase field was expressed as a linear function of 1/(wt pctFe/wt pctSiO 2 ), wt pctCaO, wt pctMgO, and wt pctAl 2 O 3 . The positions of each of the liquidus points (wt pctFe)/(wt pctSiO 2 ) at a fixed temperatures in the tridymite primary phase field were expressed as linear functions of wt pctCaO, wt pctMgO, and wt pctAl 2 O 3 .

Phase Equilibria of “Cu2O”-“FeO”-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

“…The 100 wt pct normalized results of EPMA measurements are given in Tables II and III. The present study has shown that the precipitated iron oxide phase contains a significant concentration of other components including Mg, Al, Cu, Ca, and Si. To be consistent with other publications [22][23][24][25][26][27][28][29] as well as with FactSage (version 5.3.1), [28,29] this phase is referred to as ''spinel'' in the present work with the understanding that in some other sources it could be referred to as ''magnetite. ''…”

“…This technique has been used recently by the authors to construct the phase equilibrium diagram for the ''Cu 2 O''-''FeO''-CaO-SiO 2 slag system at a controlled oxygen partial pressure and metallic copper saturation at the conditions relevant to the copper converting slag system. [21][22][23][24][25][26][27] In the present study, the experimental technique has been extended further and applied to characterize a range of compositions and temperatures at a fixed oxygen partial pressure directly relevant to the copper slag-cleaning process.…”

Influence of alumina on physical properties of an industrial zinc–copper smelting slag Part 3 – melting behaviour

“…They have reported an enlargement of the liquid phase area due to alumina addition; however, the range of their investigated oxygen potentials and CaO contents was not applicable for zinc slag fuming processes. An extensive research effort has been devoted by Jak and co-workers towards the determination of the liquidus temperature and phase equilibria in systems relevant to base metal extraction slags (Henao et al, 2010a;Henao et al, 2010b;Jak et al, 2008;Zhao et al, 1999b). Zhao et al (1999a) have investigated the influence of alumina on the liquidus temperatures of synthetic fayalite slags, at iron saturation, using the equilibration and quenching technique.…”

Experimental Study of Ferrous Calcium Silicate Slags: Phase Equilibria at $$ {\text{P}}_{{{\text{O}}_{2} }} $$ Between 10−5 atm and 10−7 atm

“…It was shown that with careful attention to factors, such as, oxygen partial pressure, temperature, technique of measurement, sample preparation and sample quenching method, accurate measurements of phase equilibria of these slag systems can be obtained. [7] The approach has been used successfully in the investigation of various complex ferrous calcium silicate slags, for example, ''FeO''-CaO-SiO 2 -''Cu 2 O'', [8] ''FeO''-CaO-SiO 2 -Al 2 O 3 -MgO, [9] and ''FeO''-CaO-SiO 2 -''Cu 2 O''-Al 2 O 3 -MgO. [10] In the current study, the equilibration/quenching/ EPMA techniques have been applied to determine accurately the phase equilibria of ferrous calcium silicate slags at intermediate oxygen partial pressures.…”