Experimental Liquidus Study of the Binary PbO-CaO and Ternary PbO-CaO-SiO2 Systems
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Phase equilibria of the binary PbO-CaO and ternary PbO-CaO-SiO2 systems have been investigated at 870-1655 °C for oxide liquid in equilibrium with air and solid oxide phases: tridymite or cristobalite SiO2, pseudowollastonite CaSiO3, dicalcium silicate (Ca,Pb)2SiO4, tricalcium silicate (Ca1−xPbx)3SiO5 (x < 0.03), new phase tricalcium-lead silicate (Ca0.8Pb0.2)3SiO5 (Ca12Pb3Si5O25), lime CaO, and calcium plumbate Ca2PbO4, covering the ranges of concentrations not studied before. High-temperature equilibration on primary phase or inert metal (platinum, gold) substrates, followed by quenching and direct measurement of the Pb, Ca and Si concentrations in the phases with the electron probe x-ray microanalysis (EPMA) has been used to accurately characterize the system. Liquidus phase equilibrium data of the present authors for the PbO-CaO-SiO2 system are essential to obtain a self-consistent set of parameters of thermodynamic models for all phases.
Keywordslead lime phase diagrams silica slags
The authors would like to thank Nyrstar (Australia), Outotec Pty Ltd (Australia), Aurubis AG (Germany), Umicore NV (Belgium), and Kazzinc Ltd, Glencore (Kazakhstan), and Australian Research Council Linkage project LP150100783 for their financial support for this research. The authors are grateful to Prof. Peter C. Hayes (UQ) for valuable comments and suggestions, to Ms. Suping Huang (UQ) for assistance with conducting experiments, and to the staff of the University of Queensland Centre for Microanalysis and Microscopy (CMM) for their support in maintenance and operation of scanning and electron microprobe facilities in the Centre.
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