Supplemental Proceedings: Volume 2: Materials Properties, Characterization, and Modeling TMS (The Minerals, Metals & Materials Society), 2012 THERMODYNAMIC MODELING OF PEIRCE-SMITH CONVERTER SLAG AT THE CHAGRES SMELTER, CHILE N. Cardona 1 , P.J. Mackey 2 , P.Coursol 3 , R. Parada 4 , R. Parra 5 Kingston Process Metallurgy, Kingston, Ontario, K7P 1P2, Canada 2 P. J. Mackey Technology Inc., Montreal, Quebec, H9J 1P7, Canada 3 Coursol Consultants, Sept-Iles, Quebec, G4R 2G4, Canada 4 Chagres Smelter, Anglo American; Camino Troncal s/n. Catemu, Chile 5 University of Concepción; C/Edmundo Larenas 285, 4070371, Chile Keywords: Copper, converting, slag cleaning, thermodynamic modeling. Abstract Flash furnace matte at the Chagres smelter in Chile is converted to blister copper in Peirce-Smith converters. The produced slagfromeach of the two slag blows is transferred to the slag cleaning furnaces (along with flash furnace slag) for cleaning prior to discharge, while the high copper slagfromthe copper blow is recirculated back to the converter process. The performance of the slag cleaning furnace is dependent in part on the quality of the converter slag. In order to understand the impact of converter slag quality on slag cleaning and to help optimize the slag cleaning operation, thermodynamic modeling of the converter slag, supported by microscopic examination of smelter slag samples, was carried out to characterize the Peirce-Smith converter slag. The results of the investigation are described and discussed in this paper. Introduction The Chagres Smelter, a unit of Anglo American PLC is located 80km north of Santiago, Chile. With a nominal capacity of 600kt of dry concentrates per year. The plant produced 145kt of copper anodes in 2010. Figure 1 presents a simplified diagram of the smelter. Figure 1 .Chagres Smelter Flow Diagram (2009) 117