Thermodynamic simulation model of the isasmelt process for copper matte
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I.
INTRODUCTION
A 15 tons per hour Isasmelt pilot furnace was installed at Mount Isa, Australia, in April 1987 for producing copper matte from sulfide concentrates, t~ The pilot plant produced a wealth of technical data, including data "about the behavior of minor elements, t~,2,31 A full-scale commercial furnace was started up at Cyprus, AZ, in June 1992, and another was started up at Mount Isa in August 1992. The main feature of the Isasmelt furnace is the single top-entry lance, as shown schematically in Figure 1. The present thermodynamic model was developed to scale up the pilot plant data for full-scale furnaces, with an emphasis on the distribution of zinc, lead, arsenic, antimony, and bismuth, as well as the heat and mass balances for copper, iron, silicon, oxygen, and sulfur in the furnace. The Isasmelt furnace with lance feeding is technologically unique in that its aim is the enhancement of both the oxidation of chalcopyritic concentrate and the reduction of overoxidized slag with lump coal in one vessel. To simulate the furnace chemistry, a two-site model was put forward. This article presents the mathematical description of the two-site model together with a critical compilation of the thermodynamic data, and it compares the model predictions with observed process performances.
II.
CRITICAL SELECTION OF THERMODYNAMIC DATA FOR MATTE AND SLAG
The standard Gibbs energy data (AG ~) to be used in the model have been chosen critically, as listed in M. NAGAMORI is with the Centre de Recherches Mingrales, SteFoy, Quebec G1P 3W8, Canada. W.J. ERRINGTON is with Mount Isa Mining Holdings Ltd., Brisbane, Queensland 4000, Australia. P.J. MACKEY and D. POC~I are with Noranda Technology Centre, PointeClaire, Quebec H9R IG5, Canada. Manuscript submitted December 15, 1993. METALLURGICAL AND MATERIALS TRANSACTIONS B
T a b l e I [4-71 as functions of temperature T (Kelvin). The
data for AsS (g), SbS (g), BiS (g), and As20~ (g) are quoted from the recent recalculations. ~6j The Raoultian activity coefficients (3,) of As, Sb, Bi, ZnS, and PbS at infinite dilution in copper matte are shown in Table II. IS-~lj It is known ttz,13} that the partial pressure of $2 increases some 20 times over an increase of only 0.4 mass pct S between copper saturation and stoichiometric CuS05 (1). Roine and Jalkanen tsj observed that the activity coefficient of As increased about 120 times at 1473 K with an increase of only 0.6 mass pct S from Cu saturation to stoichiometric CuS05 (1), and that of Sb showed an increase of about 100 times over the same small sulfur concentration range. The activity coefficients of As and Sb in the pseudobinary CuS0.5-FeS matte were recalculated by Chaubal and Nagamori 16J from the experimental data of Roine and Jalkanen tsl by using the more recent standard Gibbs energy data. [141 The increases of 3'A~ and 3'sb between Cu saturation and the pseudobinary CuS05-FeS system are also more than 100 times, as shown in Table II. The newly calculated activity-composition relations for the FeO-FeO~ 5-SiO2 slags ar
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